Note: Descriptions are shown in the official language in which they were submitted.
The present invention refers to e~ulpMont for ultrasonic tcsting of
tubes or pipes and more particularly, the invention relates to a test stand
for the ultrasonic testing and inspection o tubes or pipes in which pipes
and tubes of different wall thickness-to-diameter values (T/D ratios~ can
be tested.
The testing of tubes or pipes as to flaws and deects, using ultra-
sonic beams and using further the immersion techni~ue, i.e. using water as a
coupler fluid for coupling the ultrasonic transducer to the pipes material,
require a specific angle of incidence o~ the ultrasonic beam in relation ~o
a normal on the tube or pipe surface, through the point of entrance of the
beam into the wall of the ~ubes. Upon entering the tube's wall, the test
beam undergoes reraction because the tube/fluid interface is also a discon-
tinuity as far as the propagation of sonic and ultrasonic vibrations is con-
cerned. The angle o refracted radiation beam to that normal will in the
ollowing be called the test angle of refraction, because it resul~s from
refraction of the incident test beam as it is being refracted via in ~he
water-tube material interface. It was found that for each particular type
of tube and pipe, as defined by a specific T/D ra~io, and for a specific
material Ce.g. steel), ~here is bu~ one such tes~ angle of refraction ~or a
useful test beam. However, depending upon the T/D ratio, the test angle of
refraction varies greatly and may be as low as 33, as high as almost 90C,
this being true partlcularly if transversal waves are being employed.
In our co~pending Canadian application, Serial No. 272,059, filed
February 18, 1977, we have proposed a method to vary the test angle of re- ~ ~
fraction through temperature control of the coupler 1uid. ~ - -
It is an object of the present invention to provide a new and im-
proved system which permits rapid selection of the needed test angle o:E re-
fraction covering a very wide range or responding to a wide range of difer- -
ent pipes and here particularly a wide range of T/D ratios.
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The present inven~ion represents an improvement over the invention
disclosed in the above-idcntified co-pending application.
In accordance with the preferred embodiment of the present inven-
tion, it is suggested to provide a plurali~y test head tanks, each contain-
ing one or more ultrasonic test transducers and each being mounted in the
respective tank at a fixed orientation. These orientations differ for the
various transducers in the same as well as in different test tanks. In
addition~ sources for cold and hot water are provided as well as means for
mixing appropriate amounts of hot and cold water for charging one of these
test tanks, being used for test purposes. The angle of incidence of the test
beam as provided by a particular transducer is fixed, but the angle of re-
fraction varies in accordance with the selected tank water temperature.
Each transducer as fixedly mounted, in conjunc~ion with a rather wide range
of temperatures for the tank water, permits establishing different test
angles of refraction within a particular range. The different transducer
orientations in co~junction with the same temperature range establish
different ranges for ~he test angle of refraction to be used in inspecting
a wide variety of pipes. The transducer themselves have orientations defined
by discrete and fixed angles; the temperature adjustment of the tank water
permits stepless coverage of the entire range of angles needed.
According to a broad aspect of the present invention, there is
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provided in a system for ultrasonic inspection of tubes or pipes using
transducer means for providing ultrasonic radiation through a fluid coupler
medium towards the surface of a pipe or ~ube to be refracted at the surface
upon entering material of the tube or pipe under a particular test angle of
refraction~ comprising: the transducer means being a plurality of trans-
ducers having different orientations to an axial plane normal through the
surface of a pipe so that radiation launched by the transducers of the
plurality have different angles of incidence upon the surface; tank means
in which saîd transducers are disposed and holding said coupler medium for
establishing a refracting interface for ultrasonic radiation with the pipe
as directed by the transducers at said orientations; and means for providing
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coupler fluid to said tank means at adjustable temperatures, so that for
each of said transducers and for a sim:ilar range of adjustable temperatures,
di:Eferent ranges for the set of re:Eraction result in the pipe, only one
transducer of the plurality being used for a particular pipe of particular
dimensions to obtain a particular test angle of refraction in one of said
ranges of angles.
The invention will IIOW be described in greater detail with refer-
ence to the accompanying drawings, in which:
Figure 1 is a somewhat schematic top view of equipment in which
the preferred embodiment of the present invention is practiced; -
Figure 2 is a diagram in which test angles of refraction are :
plotted
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against wall thickness-to-tube diameter ratios and def;ining, in additlon,
several test ranges; and
Figure 3 is a cross-section ~hrough a portion of the equipment
showing primarily certain angular relations relevant in the system of the
preferred embodiment.
Proceeding now to the detailed description of the drawings, Figure
1 shows the following equipment. A roller track 4 is provided for moving
tubes or pipes to be tested in longitudinal direction into and through a
~est station on test stand. The system further includes a roller track 5
for withd~awing such a tube or pipe from the test stand. In the essence,
the test stand is comprised of a frame which includes two rails 3. A plural-
; ity of altogether three carriages 1, la, and lb, are mounted for movement on -
the rails 3. The rails are oriented to provide for carriage movement trans- ~-
versely to the direction of movement of a pipe through the station which is
also the direction of movement imparted upon objects by the roller tracks
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and 5.
` Each of these carriages is basically a water tank permitting
immersion of a portion of a pipe passing through, provided that particular
tank and carriage is placed in the path of the pipe as it is being moved by ~'
the roller tracks ~ and 5 through the station. The tanks 1, la, and lb, each
include two pairs of transducers, 2 and 2'. The transducers of each pair
are mounted in a common holder such as shown in Figure 3 for the transducers
` 2 in holder 12. The transducers of ~he other pair in the same tank, 2', are
not shown in Figure 3, but they are disposed symmetrically to a vertical plane
in the tank, being a vertical plane of symmetry for that particular tank. A
tank is in test position in the station when its vertical plane of symmetry,
as defined, is located so that the axis of a pipe as it is being transported
by the roller tracks through the test station, runs in that plane.
A particular plane is denoted with reference numeral 11 in Fi~ure
3. However, plane 11 is, in effect, inherent in the roller track and trans-
port equipment, and not in each of those individual
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test tanks such as la, lb, etc. Thus, it is necessary (a~ to position one
of these tanks, 1, la, or lb, so that its vertical plane of symmetry, as
defined between and by the respective two pairs of transducers 2 and 2', will
coincide with the plane 11; it is further nec0ssary (b) to move a pipe through
the station so that its axis moves in that plane 11.
Each of these individual transducers, regardless in which tank
they are positioned, and regardless whether they pertain to the set 2 or 2',
are oriented and fixedly mounted within each of the respective tanks 1, la,
or lb, so that the respective transducer radiates a beam towards the pipe,
whatever its diameter and whatever its wall thickness as passing through the
station. More specifically, each transducer, 2 or 2', directs an ultrasonic
beam at a particular angle aw to the vertical plane of symmetry of the tank, -
and if that plane coincides with the vertical plane 11, in which moves the
axis of a pipe passing through, then the transducer radiates at that angle
aw in relation to that plane 11. It must now be observed that plane 11 inter-
sects also the pipe's outer surface at the lowest point and the transducers
must be positioned so that the particular beam intersects the outer pipe's
surface at the point of intersection with plane 11. Therefore, plane 11
defines also the plane of incident of the radiation test beam, and ~w is,
therefore, the angle of incidence of the test beam upon the tube or pipe.
Each of the altogether six transducers 2 establishes a different
angle of incident aw or ~w ~ as shown in Figure 3 for two transducers of a
pair as = unted in one tank. Of course, for each such transducer 2 there is
another one 2', having the same angle of incident but in the opposite orient-
` ation as far as the plane 11 îs concerned.
By way of example, the six transducers 2 are mounted to their
respective tank plane of sym~etry to establish respectively the following six -
angles of incidents:
aw: 23.43; 22.3; 20.56; 19.16; 17.88, and 16.69. These are,
of course~ the angles of incidence for the respective transducer beams when a
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pipe has a position in the station so that the vertical plane through the
pipe's axis coincides with the tank's plane of symmetry and with the plane 11
as defined by the roller tracks and the s~ation as such.
The test station includes valves 21, one for each of the tanks 1,
la, lb, leading to a manifold 22 which, in turn, connects to through valves
23 to either of two mixing tanks 8. Each mixing tank 8 can be charged with
ho~ water from a source 6 or with cold water from a source 7. Suitable
metering of the flow of hot and cold water into a mixing tank 8 permits
rather rapid establishing of water at a particular temperature. The tanks 8
as well as tanks 1, la, lb, may be equipped with heaters and adjustable thermo-
stat control to maintain the water temperature as having resulted from the
initial mixing.
The speed of sound waves and ultrasonic waves through water is
greatly dependent upon the temperature. If the angle of incidence of a beam
traversing water is constant, the angle of refraction of that beam into the
`~ pipe's material depends Oll the water temperature. Thus, one obtains diferent
angles of re~raction, if the water temperature varies. The angle of refract-
ion of the two beams as shown in Pigure 3 are denoting ~st and ~st'. These
angles depend on the water temperature for a particular angle of incidence
~w ~'w) in each instance.
The following impor*ant aspect should be considered, having been
mentioned briefly earlier. First of all, for each specific - ratio, one needs
a specific orientation for the test beam in the pipe's material, i.e. one
needs a specific test angle of refraction ~st. Secondly, for a fixed
orientation of a particular transducer, one can vary the angle of refraction
simply by changing the temperature of the water.
Figure 2 now shows a number of test ranges which are defined in
- that each of them is established on the basis of a specific ph~sical orientat-
ion to the plane ll. That is to say, the ranges I through VI are associated :
with transducer adjustments as per the above-identified list for the six
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angles, from 23.43 to 16.69. The angles as plotted along the ordinate
in Figure 2 are angles of refraction in steel, aSt; each range I to VI being
specifically defined by a range of such test angles of refraction aSt. Each
range is established through water temperature variations, whereby in each
instance the upper limit is associated with 5 tank t0mperature and the lower
- limit is associated with 40C tank temperature.
The abscissa shows thickness-to-diameter ratios, and the line 30
is the characteristic curve associating these T/D ratios with specific test
angles of refraction a t needed for ultrasonic inspection. Consider now the
case of TD ratio of .1. The diagram shows that in this particular instance
one needs a test angle of refraction a5t of 52.4. In accordance with the
diagram, this is the border between test range II and test range III. Test
range II is established by a transducer having orientation to produce the
angle of incidence aw = 22.3 A The lower limit for the test range II as far
as angle of refraction is concerned, is at a5t = 52.4, and requires a water
temperature of 40C. Range III is established by a transducer orientation
for an angle of incidence aw = 20.56, and the upper limit for that range
requires a tank temperature of about 5 to produce a test angle of refraction
of ~st = 52.4.
It can thus be seen, this particular test angle a5t = 52.4 for an
DT ratio of .l is attainable with two of the transducers 2, one being operated ~ -
at a high tan~ water temperature, and the other one at the low tank tempera-
ture limit. The situation is somewhat different for a T ratio of .15. Here, -
the needed test angle of refraction Eor the test beam is 42. This clearly
falls into the test range V. The particular transducer is adjusted for an
angle of incidence ~w = 17.88, and the particular test angle of refraction
of aSt = 42 is obtained by maintaining a bath temperature of 19.7C. ~-~
The individual transducers with vibrators are mounted in pairs in
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particular holders such as 12, which, in turn, are mounted in a particular
orientation in the respective tanks. They are mounted in a fashion for main-
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taining securely a pre-adjusted disposition of the resulting direction of a
beam as emana~ing from the transducer. The two transducers have, of course,
different orientations within the holder. Preferably, they establish two
juxtaposed ranges. For example, tank 1 holds the two transducers for ranges
I and II. Tank la holds the transducers for ranges III and IV, and tank lb
holds the transducers for ranges V and VI. This means that the two transducers
2 in ~ank 1 establish angle of incidences aw of 23.43 and 22.3. The two
transducers 2' in the same tank provide for the same angles aw, but from
opposite sides of the vertical plane of symmetry as defined (being plane 11
` 10 when the tank is in test position). The other ~ransducers have analogous
orientations as can be taken from the list for aw above.
- Generally speaking, the particular example shown in Figure 3,
depicts two transducers providing, respectively, angle of incidences aw and
aw' in relation to the normal plane 11 on the bottom portion of the surface
of an immersed pipe. Each of them will produce a particular test angle of
~- refraction aSt, a'St, resulting in two different transversal waves, 9 and 9'.
Each of these angles aSt and a' t can be varied by varying the temperature of
the tank water whereby such temperature variation covers a particular range
; ~ and that gives rise to the test ranges as outlined above. The tank holds a
~ 20 second tra~sducer pair 2' which has been omitted.
- It can, thus, be seen that test angles of refractions aSt from about
37.3 to about 65 can be obtained by temperature control and under utilizat-
ion of six transducers with six fixed different ~ngles of incidents ~aw), ~ ~
differing from each other by less than two degrees. The six ranges I to VI ~ -
are, thus, established as follows: ~ :
Ranges w aSt(5C) ~ aSt (40 C)
; I 23.43 65 58
II 22.3 58 52.~
III 20.56 52.4 47.9
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IV 19.16 ~7 9 ~
V 17.88 ~ ~o ~
VI 16.69 ~0.4 37.3
The system as described operates as follows. First of all, it must
be determined what the particular TD ratio is of a pipe that is about to enter
the test stands via the roller track ~. It may be assumed that, for example,
the D- ratio is .15. Therefore, the operator knows tha~ he will have to use
test range V. He will, therefore, place the particular one of the three tanks,
for example tank lb, into the operating range of the test stand, the others
are shifted aside. In addition, he will determine from the chart of Figure 2
what the particular test angle of refraction a5t is; ~he chart tells him that
the needed angle is 42. He will now choose the desired temperature and
obtain the requisite mixture in tank 8 through appropriate metering and timed
connection of one of the tanks 8 to the heater 6 and the cooler 7. Having
produced the requisite mixture in one o the tanks 8, tan~ lb is now charged ~ ;
with the liquid. It may be desirable through control to maintain the tempera-
ture of the tank at the desired setting. As the pipe arrives, the operator
will conduct the test using the transducer which provides an angle ~w of
17.88. As stated, the temperature is set to 19.7 and that will produce an
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angle of refraction of ~s~ = 42. The temperature must be maintained constant
within the permitted tolerance range which is not too large throughout the
test, i.e. throughout the passage of the tube or pipe through the test stand. - -
If now a pipe of a different TD ratio is about to arrive, the opera-
tor has to determine whether or not the T ratiofalls within the same test
range in which case he does not have to change the test tank. Otherwise, he
has to place a different tank into the test stand and procede as described
above.
One can see a modification of the invention system depending upon
the available space. Conceivably, the different test tanks 1, la and lb, may
all be permanently positioned in line with the propagation and transport path ;~: :
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of the pipes so that a transverse displacement and carriage a~justment is
not necessary; one simply operates thc respective transducer in that
particular tank which in conjunction with a particular tank temperature covers
the particular D value.
The invention is not limited to the embodimen~s described above
but all changes and modifications thereof not constituting departures from
the spirit and scope of the invention are intended to be included.
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